Retinitis pigmentosa (RP) is a congenital disease associated with progressive retinal degeneration and possible eventual blindness. The overall goal of the current project is to find psychophysical procedures which effectively discriminate potential RP patients from the visually normal population. At present, the earliest indication of the disease is given by an electroretinogram (ERG) record characterized by abnormal latency and time-course. This fact suggests that RP patients will perform abnormally on psychophysical tests which measure sensitivity to temporal changes in luminance. We have designed psychophysical tests of two-flash resolution and of temporal modulation (flicker) sensitivity. These tests have been administered to a small number of known or suspected RP patients: preliminary data indicate abnormalities with respect to control groups. Future plans include the design and implementation of the following additional measures of temporal sensitivity: visual reaction-time, rapid dark adaptation, temporal integration, and temporal enhancement. These tests will be controlled by a program executed by a microcomputer incorporated into the visual stimulator itself. We plan to administer these tests to known or suspected RP patients and to populations of subjects at risk of RP. By correlating the resulting data with ERG and other ophthalmological measures, it should become possible to identify those psychophysical measures which reliably detect RP at its early stages.